Well jarring tool



T. A. ANDREW WELL JARRING TOOL April 14; 1959 Filed Aug. 22, 1955 INVENTOR.

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United States Patent O WELL JARRIN G TOOL Thomas A. Andrew, Newport Beach, Calif.

Application August 22,1955, Serial No. 529,759 6 Claims. (Cl. Z55-27) This invention relates generally to well drilling apparatus and more particularly to jarring tools.

In the drilling and maintenance of wells, such as oil Wells, it is frequently necessary to loosen drill strings or other items of drilling equipment that have become fast in tle well bore. These items are commonly referred to as sh.

According to one procedure for removing the fish, a fishing string, including a jar, is run into the bore and attached to the fish by means of a spear or overshot. A strain is then taken on the string and the latter, owing to its elasticity and length, is stretched a substantial amount. At a predetermined pull on the string, mechanism within the jar is released and the elasticity of the stretched drill string provides a force which accelerates the mass of the drill pipe upwardly. Upward movement of the string is arrested by engagement of a hammer, carried on the string, with an anvil to produce an impact of substantial intensity which tends to loosen the fish.

Existing jars of this type are, however, decient in that in the interval between release of the mechanism and engagement of the hammer with the anvil, the section of the string extending between the jar and fish, through which the impact is transmitted to the fish, is momentarily released to drop downwardly in the well bore so that the strain on this section and on the sh is relieved. The effectiveness of the subsequent impact of the jar is, therefore, diminished to the extent of the energy required to restore this strain.

Further, the hammer of such jars is rigidly fixed to the drill pipe so that the impact acts equally on the drill pipe above the jar and surface equipment as well as on the drill pipe below the jar and the fish. Inasmuch as in certain wells only relatively light pipe is available for such jarring operations, the intensity of the blow which may be struck is severely restricted by the ability of the pipe to withstand the impacts. Also the transmission of high intensity impacts to the surface occasioned by the use of these jars often results in damage to the drill rig and injury to operating personnel.

It has been determined that the type of blow which is most effective in removing a fish varies with the different conditions under which an object may become stuck in a well bore. For example, where a fish is held in a4 sand formation, a series of rapid sharp blows, or impacts of short duration, are the most effective.

Since, in existing jars, the hammer is rigid on the drill string, the mass of the hammer is combined with that of the string, and owing to the substantial mass involved, short duration impacts cannot be produced.

Various types of so-called hammer jars have been developed in an attempt to produce sharper impacts and to restrict the latter to the fish. Generally, these hammer jars embody a separate hammer of relatively small mass whichis movable with respect to the drill string and which is depressed against the action of a spring by mechanism operated by rotation of the drill string. Upon being released, as by a strainl being taken in the string,

Patented Apr. 14, 1959 "ice the hammer is driven by the spring into impact with an anvil to produce a sharp impact that is transmitted mainly to the fish and substantially isolated from the drill string extending to the surface. This type of hammer jar is effective in those situations requiring sharp blows but is limited in its application owing to the necessity of rotating the drill string to reset the hammer and by the fact that only relatively small springs can be housed within a jar so that the intensity of the impact is severely restricted.

A broad object of this invention is the provision of jarring tools which avoid the above and other deficiencies of existing jars.

A more specific object of the invention is the provision of a Well jar which is effective to deliver relatively high intensity impacts of short duration mainly to the fish and a strain on the fish during the jarring operation.

Another object of the invention is the provision of a hammer-type well jar wherein the impacts produced are substantially isolated fromthe surface equipment so that blows of greater intensity may be safely produced.

Still another object of the invention is the provision of a hammer-type well jar which, while producing relatively high intensity impacts, may be run on light tubing or cable.

Yet another object is the provis-ion of a hammer-type jar wherein an initial strain may be taken on the fish and maintained during movement of the hammer into impact With the anvil and wherein resetting of the hammer is accomplished without rotation of the drill string or re- .leasing of the initial strain on the sh.

A further object of the invention is the provision of a jarring tool which may be run with a conventional straight pull jar for increasing the effectiveness and reducing the surface impact of the conventional jar.

Yet a further object is the provision of a booster jar to be run with a conventional jar which operates to produce an impact so synchronized with the impact of the conventional straight pull jar for increasing the effectiveness and reducing the surface impact of the conventional jar.

Yet a further object is the provision of a booster jar to be run with a conventional jar which operates toproduce an impact so synchronized with the impact of the conventional or basic jar as to occur after the impact of the basic jar has restored the initial strain on the fish.

According to one illustrative embodiment of the invention, the jar embodies a mandrel which at its upper end` is adapted for rigid attachment to a drill string extending Ato the surface land Whichslidably mounts a hammer that normally bearspagainst an upwardly facing shoulder of the mandrel. 1The lower end of the mandrel is telescoped into the upper end of'a cylindrical casing having a downwardly facing anvil surface and is retained in a lower lposition in the casing by releasable detent mechanism or latching means. Springs bias the mandrel to its lower position in the casing land the hammer downwardly on the mandrel into abutment with the mandrel shoulder. When the jar is run on a fishing string and a strain is The hammer is moved upwardly on the mandrel into impact with the anvil` surface while the energy of the upwardly moving mandrel and drill pipe attached thereto l will be relatively gradually absorbed by the mandrel biaysing spring so that substantially no impact is transmitted through the tfishing string to the surface. The strength of the mandrel'biasing spring is made such that the man- 3 d'r'eI may' be re-engaged with the detent mechanism without lowering, below' a desired value, the strain on the sh. Also the hammer, following its initial high intensity impact will rebound several times between the anvil surface and mandrel shoulder' to produce a series of sharp blows.

A modied `formr ofthe invention, hereinafter referred to as a' booster jar,1 is similar in construction to' the jar just described diirering only" in the omission or die' defeat' mechanism so that except for the restraining" force ofL it's biasing spring, then mandrel is free' to' move in ther casing;

This' booster jar is run in a' nshing string with any conventional, or basic, jar which, as hereinbefore described, permits momentary' release of the strain on thefish. The arrangement of the booster jar is such that it will' impart a: series of sharp blows which are' so' synchronized with the impact' of the basic jar' as to' occur after the initial strain on the fish has been regained by the basic jy'ar.

A better understandin-g of the invention may be had from the' following. detailed description thereof taken in conjunction with"tl'1"e annexed' drawings wherein: i

Fig. f is a` longitudinal section through a well bore casing andl a` fishing stringther'ein' incorporating one form of the jar of this invention', the parts of the jar being shown in their normal positions Fig'. 2 isa v-iew similar to Fig'. 1 but with' the' parts of the jarl shown at the instant of impact;

Fig; 3' is a section taken' along line 3;-3 of Fig. l;

Fig. 4 is a section taken' along line 4-4 of Fig. l;

Fig. Sis a longitudinal section through a modified' form of jar, the parts thereof being shown in their normall positions;

Fig. 6'is a view similar to Fig. 5' but` with the'p'arts of the" jar shown at the instant of impact;l and Figs. 7' and 8 are views illustrating two ways of placing the jar of Figs. and 6'in a fishing' string.

Referring first to Figs. 1 4 of the drawings, the hammer jar 20' of the invention comprises a mandrel 21 which 'has its upper end enlarged at 22 and formed with a couplingV box 23 for connection to a coupling pin 24 on the lower end of a string of drill pipe' 25 extending to the surface. The lower end of mandrel 21 has a pair of axiallyr spaced enlargements 2'6 and 26v defining" an annular groove 27 therebetween. Intermediate the enlargements 22 and 26, the mandrel is formed' with an` integral annular abutment' 28'an'd slidable on the mandrel between this abutment and enlargement 22 is a hammer' 29';

The'hammer'has a reduced diameter lower endportion 30` terminating in an' enlarged shoulder 31 whose upper annular face 32 forms" the striking face' of the hammer. A compression spring'33' encircles mandrel 21 and abuts at one endenlargement' 22.l and at'the other end hammer 29 'so' that the latterv is biased downwardly on the mandrel intol engagement with abutment 281 Telescoped over the lower end portion of themandrel and lower portion 30 ofthe hammer is'an anvil'sleeve 34. Theperipheral surface of hammer shoulder 31 slidably engages theinn'er cylindricalsnrface35 ofI the sleeve and the` upper end of the latter is extended radially inwardly to form" an annular' shoulder 36' whose inner cylindrical surface slidably engages the end`portion'30 of the hammer'. The lo'we'r'a'nnular face 37 of the shoulder 36 Iforms an 'anvil' face against'which hammer face 32 is adapted" to strike, as' will' presently bel seen.

In the normal position of the' mandrel, hammer, and anvil sleeve, as' illustrated .in Fig. l, Ahead 31` of' the hammer' abuts anl annular shoulder 38' in' the sleeve, spaced a distance'below anvil face 37, and abutment 284 of theman'drelrests on a further" annular shoulder 39. A second' compression' spring 40, encircling the mandrel and'bearing at'one end against the lower face of shoulder 39a'n'dL at theA other end against enlargement`2`6f of'the' mandrel, biases thel latter' downwardly in" sleeve 34"'t'o saidlnormalpo'sition'. p 4

l\`/Ioun`t` ':dJ in four' equi-singularly spacedfaxialY slots 41 (see Fig. 3) in the outer surface of the sleeve 34, and fixed at opposite ends to the latter, are four spring bars 42. Intermediate the ends of the bars are integral detents 43 which extend through openings 44 in the wall of the sleeve and project into annular groove 27 of the mandrel. The corners of these detents are beveled, as indicated at 45, and the lower end of the mandrel is peripherally beveled at 46 to provide for camming ofthe detents into and out of the mandrel groove 427 during operation of the jar, to be presently described. v

The lower end of anvil sleeve- 34 is formed` with a coupling pin 47 adapted for securement in a coupling box 48 in the upper endl of a string of drill pipe 49 extending to the nsh. In a iis'hin'g operation;- the lower end of section 49 is rigidly attached, in any conventional manner, as by a spear or overshot, not shown, to the fish to be retrieved.

A passages() may extend axially through the drill strings 2'5, 49 and the mandrel 21 to provide for the now of mud lor other fluid to the fish during jarring operations to facilitate loosening of the fish. y

In use, the jar 20 is )assembled in'- the fishing string 2'5', 49 and. the latter is lowered' into the casing 5-1 of a well bore and attached, as previously mentioned', to the fish by a speargorovershot,` not shown. A strain is then taken on the drill pipe at the surface, the mandrel and anvil sleeve being locked against relative movement by detents, or latching means, 43. As the pull on the drill .string is increased, the drill pipe will stretch, and after the pull attains a predetermined value, which may be varied by changing the strength of the spring bars 42, the latching means 4 3 will be cammed outof the mandrel groove 27 resulting in outward bowing of the' springv bars, as illustrated in Fig, 2l V Upon release ofthe mandrel` from the anvil sleeve, the tensile forces produced by stretching. of the Adrill pipe 25 will upwardly accelerate the mass of the pipe, `and also hammer 29 due to itsy engagement with4 mandrel abutment 28. Upward movementvof the mandrel inthe sleeve 34' will be relatively gradually arrestedf by compressing of the mandrel biasing spring 40 so that the energy of the upwardly moving mass of drill pipe will be absorbedl over a relatively extended period of time. Thus, substantially no-impact Will be delivered tothe drillpipe 25 and transmitted therethrough tothe surface.

Hammer 29 is, however, substantially freely slidablel along the mandrel and its upward movement is suddenly arrestedv by engagement with the anvil face 37.` Theresulting impact is transmitted through sleeve 34; and drill pipe 49 to the fish. v

At the upper limit of movement of mandrel 21 in sleeve 34 (Fig. 2),y the upper face ofmandrel abutment 28 will be spaced from anvil face 37 a dista-nce which is slightly lgreater than the axial dimension of hammer shoulder 31, and the hammer, after its initial impact with the anvil 37 will rebound back audforth` between the abutment and anvil to impart` a` series of rapid, sharp blows to the ish.

Hammer biasing spring 33-l hasV a relatively low spring.y

constantv inasmuch as its` function is merely' thatl of returning the hammer to its'normalposition in contact with abutment 28 on the mandrel.

accordance with the minimum strain to be maintained onV the fish. Thus, while the strain on the fish will, after .release of the latching means, decrease substantially below the relatively highvalue of strainl taken inthe drill Mandrelbiasing springl 40 has arelatively highf spring constantsincev one of itsI gssgois String to release the latching means, it will not drop below the initial tension in the mandrel biasing spring. In resetting the jar, the strain on the drill string is relieved suciently to allow the mandrel biasing spring to return the mandrel to its normal position, of Fig. 1, wherein the detents are received in the groove 27. The bevel corners 45 of the detents and beveled bottom edge 46 of the mandrel cause outward camming of the detents as the mandrel is moved downwardly in the anvil sleeve 34 by its biasing spring 40 so that the detents will ride/over the surface of the enlargement 26 and drop into the groove 27. The above described cycle is repeated as many times as is necessary to remove the iish.

Referring next to Figs. -8, there is illustrated a booster jar 20 which maybe run with any conventional basic jar 52 for supplementing the impact of the basic jar. Conventional, straight pull jars have the previously noted delciency of relieving the strain on the iish during travel of the hammer into impact with the anvil following tripping of the release mechanism within the jar.

`Booster jar 20 is substantially identical with the jar of Figs. 1-4 differing therefrom only by the omission of the latching means including spring bars 42, detents 43, and groove 27 in the mandrel. It will be seen, therefore, that except for the biasing action of the mandrel biasing spring 40', the mandrel 21 of the booster jar is freely movable in the anvil sleeve 34'.

In use, the booster jar is run either below the basic jar 52, as illustrated in Fig. 7, or above the basic jar, as illustrated in Fig. 8. The basic jar 52 may be any conventional jar which delivers an impact when a hammer in the jar is released upon a predetermined strain being taken in the shing string 53. The mandrel biasing spring 40', in its normal expanded condition shown in Fig.` 5, has an initial tension such that it will be only partially compressed when a strain is taken in the drill pipe to release thehammer in the basic jar so as to allow for movement of the booster hammer 29.

Arelatively light hammer biasing spring 33 is provided, as in first described jar, for returning the hammer to its normal position against the mandrel ablutment 28.

Assume first that the booster is run above the basic jar 52, as illustrated in Fig. 8. Under these conditions, when the strain is taken in the drill pipe to release the basic jar, the mandrel biasing spring 40 is partially compressed, as just mentioned, and the booster hammer Z9 is spaced from the anvil 37. When the basic jar releases, the section of drill pipe above the basic jar, in which the booster is connected, moves upwardly under the action of the tension in the drill pipe. This up ward travel of the section of drill pipe between the booster and basic jar, and the anvil sleeve 34 of the booster, which is connected to the section, is suddenly arrested by engagement of the impact surfaces in the basic jar. Upward travel of the mandrel 21 is immediately thereafter arrested by the mandrel biasing spring 40', the tension in which is momentarily relieved during the interval between the release and subsequent impact of the basic jar.

This impact of the basic jar and the inertia of the hammer 29 cause the latter to strike the now arrested anvil 37', rebound, and then strike the anvil again to produce a series of rapid impacts, as in the previous form of the jar. These impacts of the booster occur after the impact of the basic jar. The impacts of the basic jar, as well as the subsequent impact of the booster jar, are effectively isolated from the section of drill pipe above the booster by the mandrel spring 40.

Assume now that the booster is run below the basic jar, as illustrated in Fig. 7. Under these conditions, when the basic jar releases, the section of drill pipe below the basic jar, and therefore the booster, move downwardly under the combined action of gravity and the tension in the latter section of drill pipe. This downward travel of the pipe section and the mandrel 21 connected thereto is suddenly arrested by engagement of the impact surfaces of the basic jar. The anvil sleeve 34', however, and the section of drill pipe therebelow, continue to move downwardly. As in the arrangement of Fig. 8, the mandrel biasing spring 40 is slightly relieved and thereby expands during the interval between release and subsequent impact of the basic jar.

The impact of the basic jar is transmitted through the lower section of drill pipe and mandrel to the mandrel shoulder 28'. This impact tends to impel the hammer 29 toward the anvil 37. with the continued downward travel of the anvil sleeve 34', after arresting of the mandrel 28', results in engagement of the hammer 21' with the anvil to produce a series of rapid impacts after the impact of the basic jar. Downward movement of the anvil sleeve 34 is arrested by compression of the mandrel biasing spring.

As previously described, the basic jar, in striking its blow, releases tension in the drill pipe extending from the jar to the iish. A substantial portion of the energy of impact of the jar is, accordingly, expended in regaining this tension and in lifting the fish to its original position if it drops slightly during the release of tension thereon. The eiect of the impact in removal of the iish is thus lessened.

The present booster jar when run with the basic jar, however, becomes operative to deliver its series of sharp impacts to the fish only after the strain on the latter has been regained. Thus, it will be clear from what has just been said that the decrease in the upward strain on the iish, which occurs immediately after release of the basic Y jar, is regained upon engagement of the striking surfaces of the basic jar to produce an impact. This up ward strain is transmitted through the mandrel biasing spring of the booster which is initially pretensed, as prejar impacts delivered to the sh while a strain is taken v thereon, intensify the impact of the basic jar and have maximum effectiveness in loosening the iish.

If the booster jar 20 is run below the basic jar 52, as illustrated in Fig. 7, its impacts will have maximum eciency due to its immediate proximity to the fish, not shown.

If the booster jar is run above the basic jar, as ill-usi trated in Fig. 8, it will tend to render the impact of the basic jar more effective and will substantially eliminate the transmissions of the basic jar impacts to the surface since it, in effect, isolates the basic jar from the drill pipe extending to the surface. In either position, the booster jar will have the effect of delivering to the fish a series of sharp blows while a strain is being exerted thereon.

While I have shown and described certain preferred forms of my invention, it will be understood that they are merely illustrative in nature and that various changes may be made in the design and arrangement of parts of the invention without departing from the spirit and scope of the following claims.

I claim:

l. A well jarring tool to be run in a shing string, com prising: a pair of telescopic members having coupling means at their free ends for connection of the jar in a fishing string, a hammer slidably mounted on one member for axial movement relative to both members, said hammer having a striking surface facing the free end of said one member, an anvil on the other member having an impact surface facing the free end of said other member and located between said striking surface and This action, in combination Thev the free'v end of said one member, said impact surface being" engageable by the hammer surface' toproduce an impact' by axial movement of the hammer towardv the free end of said one member, rigid shoulder means on" said one= member engageable with the hammer for limiting' axialmovement of the latter away from the free' end of said one member, yieldable means biasing said members toward one another to' a given normal position, wherein said hammer is spaced from the anvil, said ham'- m'er being' relatively moved toward said anvil by said shoulder means when said members are moved apart.

2. A well jarring tool to'v be run in alishing string, cornprising: a pair of telescopic members having coupling meansat their free ends for connection of the jar in a fishingstring, releasable latch means carried: on the mem'- bers for retaining the latter in a given normal position relative to one another and against axial movement under axial forces of less' than a predetermined value appiied to the members tending to separate the latter, said latch means being released to' permit axial movement of the members in directions away from one another in response to axial forces exceeding said predetermined value, a hammer axially movable relative to both mem bers, means dening an anvil on one of the members en-A gageable by the hammer to produce an impact by axial movement of the hammer away from the free end of said one member, rigid shoulder means on the' other member engageable with the hammer for limiting axial movement of the latter away from the free end of said a spring constant as to resiliently arrest axial separation of the' members to a position wherein said hammer is" capable of limited axial movement between said anvil and shoulder" means.

4.V The subject matter of claim 1 including relatively lig'l't spring means acting between said one member and hammer `for biasing the latter toward saidshoulder means.

5.- A well jarring tool to be run in a; iishing string, com-Y prising: a pair of generally tu-biilar, telescopic members, coupling means on the free ends o'f said members for connection of the jar in 'a fishing string, a tubular hammer slideably mounted on the inner one of said members and having one end slideably received within the inner end of the outer member, said inner end of the' outer'member having an inwardly' extending flange' denning anl anvil face' and said one end of the hammer having an' outwardly extendingV nange denn'ing a hammer' `ia'ce engag'e'able with said anvil face to produce an' impact by axiai movement of the' hammer away' from the free end' ofthe outer member, a shoulder on' said inner" member engageable with the hamm-er for limiting axial' movement of the' latter toward the inner end of the' inner member, spring means acting between said members for biasing the latter toward o'ne another to' a given normal position wherein said hammer face is sp'aced lfrom" said anvil face and resilien'tly' arresting axial separation. of the' members' prior to engagement of said hammer and' anvilz faces.

6. A well jarring tool to be run in a' lish'ing' string, comprising: a pair of generally tubular, telescopic rnernbers, coupling means on theA free ends of said members' for connection of the jar in a fishing. string, a t'ubiila'r hammer slideably mounted on the inner one of s'aid members and having one end slideably received within the inner end of the' outer member, saidV inner end o'f the outer member having' an inwardly extending' a'ng'e' dening' an anvil face and said one end of the hammer having an outwardly extending flange defining a hammer face errgageable with said anvil face to' produce anl impact by axial movement of the hammer away from the free end of the outer member, a shoulder on said inner' 'from one another in response to Iaxial forces exceeding said predetermined value, said hammer face being spaced from said anvil face when the members are in said normal relative position, and spring means acting' between said mel'n'bers 4for biasing the latter to normal position and resiliently arresting axial separation' of the members' prior to' engagement of said hammer and anvil faces after release' of said latch means.

References Cited in the le of this patent 

